When it comes to viruses, many people's first impression is that they are harmful to human health. With the popularization of cervical cancer vaccine, more and more people are beginning to understand that viral infection can also cause terrible cancer. In addition to human papillomavirus targeted by cervical cancer vaccine, some common viruses are also potential carcinogens, such as hepatitis B virus.
However, a common virus that lives on our skin seems to be not harmful to human health, but beneficial! According to a paper recently published in the top academic journal Nature, scientists at the Cancer Immunity Center of Massachusetts General Hospital found that some "low-risk" human papillomavirus seems to indirectly protect us from skin cancer.
According to the author of the study, "this is the first time that there is evidence in both experimental models and human bodies that common viruses may be beneficial to health, and this benefit is related to cancer protection."
First of all, these low-risk human papillomaviruses are different from the human papillomaviruses targeted by cervical cancer vaccines. Up to now, there are more than 170 known types of human papillomavirus, involving different clinical manifestations. Only about 12 of them are classified as high-risk types, such as HPV 16, 18, 6, 1 1, which are related to various genital cancers, and some are related to head and neck cancers and oral cancers. Existing vaccines can help us resist these malignant tumors.
In addition, there are many other types of human papillomavirus, such as those studied by Dr. Shawn Demehri and his colleagues. They are common * * * viruses inside and on the surface of human body and are considered to have a low risk of causing serious diseases. The most common manifestations of these low-risk human papillomavirus on the skin are verruca vulgaris, verruca plantaris and verruca plana. It is estimated that 1 person in every three school-age children is infected with human papillomavirus, which shows that infection is very common.
Previous studies have shown that the widespread infection of β subtype human papillomavirus in the population may be related to the risk of some malignant skin cancers. In immunosuppressed patients, the risk of skin squamous cell carcinoma increased 100 times. Naturally, some people will doubt whether the virus lurking in the human body all the year round will become a carcinogenic factor under the condition of low human immunity.
This is exactly the question that this study wants to answer. The authors of the study said that although many studies tried to prove the connection between human papillomavirus infection and squamous cell carcinoma, none of them could prove that human papillomavirus really promoted the development of these common skin cancers.
And the experimental results they got were just the opposite of what they thought in the past. Experiments on mouse models show that mice with complete immune system and natural immunity to human papillomavirus, as well as mice immunized by T cell infusion, can resist skin cancer when exposed to ultraviolet radiation or chemicals known to cause skin cancer. This is because the peptide molecules of human papillomavirus can induce T cells to produce immune response. Activated T cells can effectively attack early skin cancer cells.
▲ Cancer cells infected with human papillomavirus are attacked by immune cells.
In addition to animal experiments, the researchers also tested human skin cancer samples, analyzed the existence and activity of 25 known low-risk human papillomavirus, and found that the viral activity and viral load in skin cancer cells were significantly lower than those in adjacent normal skin, "indicating that they have strong immune selectivity for virus-positive malignant cells".
For patients with suppressed immune system, the risk of skin cancer is greatly increased. The researchers explained that this is due to the decline of immunity, not the carcinogenic effect of human papillomavirus.
▲ Early skin cancer colonized by human papillomavirus is like a wart of the immune system, which can be effectively removed.
Based on these findings, the researchers suggested: "Developing a T-cell-based anti-human papillomavirus vaccine may provide an innovative way to enhance skin's antiviral immunity and help prevent warts and skin cancer in high-risk groups."
At the end of the paper, the researchers pointed out that enhancing the natural immunity against human papillomavirus may further improve the effectiveness of immunotherapy when using immune checkpoint inhibitors to fight skin squamous cell carcinoma. Perhaps in the future, with the help of the power given by the virus, we can prevent and treat skin cancer more effectively.
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